Electro-mechanical clutch-brake power transmitting devices are well known in the prior art for driving machinery such as textile looms and the like. With such power transmitting devices, the flow of power from a motor to the loom is controlled by selective operation of the clutch and the brake. A problem which exists with clutch-brake type power transmitting devices concerns the response time incident to the operation of the clutch and brake. On the one hand taking up of the lost motion or slack in the clutch or brake, can be time consuming. The electrical time constant of the system including the clutch or brake solenoid coils is also a factor influencing the response time of the system.
It has been proposed heretofore to utilize relatively low voltage electrical power to maintain the clutch or brake in an operative condition but to apply intermittently a pulse of high voltage quickly to take up the slack in the clutch or brake actuation. It has been known to provide such intermittent high voltage pulses by use of a capacitive discharge system, however, the time required to recharge the capacitor after each use has limited such known systems to applications having slow rates of on-off cycling.
One type of loom operation for which the prior art capacitive discharge systems have not been adequate involves the "jogging" mode of loom operation in which the loom is repeatedly started and stopped to provide a relatively slow operation useful in diagnosing malfunction, correcting yarn breakage or the like.